Electrophoresis apparatus



May 13, 1958 E. G. r-flc'KELs ETAL 2,834,729

ELEcTRoPHoREsis APPARATUS Filed Feb. 24, 1955 4 Sheets-Shawll l May 13,1958 E. G. PlcKELs Erm. 2,834,729

ELEcTRoPHoREsIs APPARATUS 4 Sheets-Sheet 5 Filed Feb. 24, 19 55 fan/Agos. pvc/ras PML/P F. scar/ao FRED G. WML/AMS By /A/v/vrofs ATTORNEYS May13, 1958 E. G. PICKELS ET AL 2,834,729

ELECTROPHORESIS APPARATUS Filed Feb. 24, 1955 4 sheets-sheet 4/A/l/EA/TOES KW70/@MEMS ifA I/W///////ff/// F.IE E

l/ m Q/U United tes ELECTRPHRESIS APPARATUS Application February 24,1955, Serial No. 490,261

t Claims. (Cl. 204-299) This invention relates generally toelectrophoresis apparatus of the paper strip type.

In performing electrophoretic and inophoretic separations making use ofan absorbent paper strip, apparatus has been employed comprising twoelectrolyte cells with means whereby a paper strip is supported with itsends dipping into the electrolyte. Commercially available apparatus ofthis type has been subjected to certain disadvantages. Particularly manyof the manipulations involved have been troublesome and time consuming.In order to equalize the electrolyte levels in the two cells aconnecting tube has been employed with a pinch cock. Care must be takento permit equalization through this tube before a test run is commenced.The practice of permitting the strips to dip into the electrolyte istroublesome in that it tends to provide uneven and excess wetn ting,particularly at the time the strips are removed for drying. Removal ofthe strips at the end of a run is troublesome, and requires individaulhandling to transfer the strips to a dryer.

In general it is an object of the present invention to provide improvedapparatus of the above character which will avoid the above mentioneddisadvantages of prior equipment.

A further object of the invention is to provide apparatus i of the abovecharacter having means for equalizing the levels between the electrolytecells without the use of conventional expedients. f

Another object of the invention is to provide electrophoresis apparatushaving novel means for effectively connecting the end portions of thestrip to the electrolyte, without causing excessive wetting, and withouthaving excessively wet end portions when the strip is removed.

Another object of the invention is to provide an electrophoresisapparatus of the above character in which special means is provided forapplying the strips and for removing them for the drying operation.

Additional objects and features of the invention will appear from thefollowing description in which the preferred embodiment has been setforth in detail in conjunction witb the accompanying drawing.

Referring to the drawing:

Figure 1 is an elevational View in section showing apparatus inaccordance with the present invention, the view being taken along theline 1-1 of Figure 2;

Figure 2 is a side elevational view in section and taken along the line2 2 of Figure l;

Figure 3 is an exploded view illustrating various parts of theapparatus;

Figure 4 is a cross sectional detail on an enlarged scale, taken alongthe line fi-4 of Figure 3;

Figure 5 is a partial elevational view showing another embodiment ofapparatus in accordance with the present invention, the view being takenalong the line 5-5 of Figure 6; and

Figure 6 is a partial elevational View in section taken along the line6-6 of Figure 5.

The apparatus illustrated in the drawing consists of 2,834,729 PatentedMay 13, 1958 "the a container 10 which forms in effect a base for theapparatus and which provides the separate compartments or electrolyticcells 11. A central vertical partition wall 12 extends between the endwalls 13, and is sealed with respect to both the end walls and thebottom wall 14. The lower edge of the partition 12 is provided with agroove 15 which is relatively small in section, and which communicatesat its ends through the ducts 16 with the two cells 11. This grooveforms an elongated passage lled with electrolyte whereby equalizationmay occur between the two cells 11 without however permitting anysubstantial amount of diffusion between the cells. The effectiveelectrical resistance of the electrolyte in the groove 15 is relativelyhigh and therefore the current flow through the same is negligible.

A pair of wire electrodes 17 extend through the cells and are carried bysuitable means such as the support knobs 18. At one end of the apparatusthe wire electrodes 17 connect with the terminals 19.

Each cell is preferably provided with a plurality of bales to isolatethe region occupied by the electrodes 17, from the regions whereelectrical connection is being made to the ends of the paper strips.Thus each cell is provided with spaced vertical baflles 20 and 21, whichare sealed at their edges with respect to the end and bottom walls 13and 14. in addition each cell is provided with the batiles 22 and 23,which have their lower edges terminating short of the bottom wall 14.Also the latter baies have their ends slidably engaged in grooves formedin the end walls 13, thereby permitting their removal.

A paper strip support 26 is removably carried by the container 10. Thissupport consists of spaced vertically extending end members 27, whichare attached to the ends of the rigid tube 28. The upper end portions ofmembers 27 are connected by the parallel paper strip supporting rods 29.The lower extremities of the end members 27 are slotted as indicated at31, to accommodate the end portions of the central partition 12.

In addition to the strip supporting means 26, we pro vide a special rack32 which Ais used for applying and removing the strips. This rackconsists of side portions formed by two-pairs of arms 33 `and 34, havingcorresponding ends pivotally connected together by the hinge bolts 36.The other ends of the arms are connected toe gether by the rods 37. Atthe free ends of the arms we provide wing-like extensions 38 and 39,which overlap when the arms are swung together to the position shown inFigure l. The hinge bolts 36 are provided with studs 40 adapted toengage in the slots i2 provided in the upper ends of the members 27.Also they are provided with Bellville or similar spring washers 41 toprovide some frictional resistance to hinge movement. Each of the rods37 is provided with a plurality of strip engaging studs 43, which areadapted to engage paper strips as will be presently described. Theextremities of these studs are provided with enlarged heads r44.

In addition to the baffles previously mentioned, we provide the baillewalls 46 which are interposed between the batlles 21 and the side walls47 of the container. The lower edges of the bales 46 terminate short ofthe bottom wall 14, and the upper portions i8 extend a substantialdistance above the normal electrolyte level. The

portions 48 serve to accommodate wick-like members y 49 which can beformed of absorbent material like blotting paper. Normally the loweredges of members 49 dip into the electrolyte as illustrated in Figure 1.As convenient means for retaining the wick-like members 49 upon thebales 46, we provide button-like member studs 51 which engage slots 52in the ends of the corres ponding wick member 4S. This arrangementpermits ready application and removal.

It is desirable to provide the apparatus with a suitable removable cover53. The lower edge of this cover seats upon the upper edges of thecontainer, and the upper end is provided with an elongated accessopening S4 (Figure 2). A closure 56 is provided for the opening 54, andis shown provided with inner locking lips 57, whereby upon sliding theclosure in one direction or the other, it can be removed.

Suitable materials can be used for the various parts. The container andthe various batiles can be made of a plastic insulating material, suchas a material that is transparent. The same material can be used for theside members of the support 26, and the arms of the rack 32 and thecover.

Although the apparatus has been described with reference toelec-trophoresis apparatus of the paper strip type, it is to beunderstood that other media such as silk cloth, glass fibers,gelatin'ous sheeting land other materials hav- .ing the desiredcapillary action may in special circumstances fbe employed. It isfurther noted that the paper as well as the other materials may be soproportioned as to be considered sheets, bars, rods or `tubes ratherthan strips.

Operation of the apparatus described above is as follows: A suitablequantity of electrolyte at the required pH is introduced into the cells1l, and the wick members 49 applied. The level of electrolyte in the twocells equalizes through thegroove or duct 16. A number of absorbentpaper strips S8, each provided with an aperture adjacent its end, areengaged with the studs 43 of the hinged rack 32, while this rack isextended on a suitable supporting surface. The hinge rack 32 is nowapplied to the support 26, with engagement of the studs 4G in thegrooves 42, after which the two sides of the rack 32 are swungdownwardly to the inal position illustrated in Figures l and 2. As thetwo sides of the rack are swung downwardly the central portions of thepaper strips bend over the strip supporting rods 29, substantially asshown in Figures l and 2. In addition the extremities of the paperstrips come into contact with the wick members 49, and are caused to bespaced from the rods 29 (Figure l). By means of a suitable syringe allof the paper strips are wet with electrolyte. By virtue of such wetting,and also because of absorption from the cells, the wick members 49become thoroughly saturated, together with the strips. The extremitiesof the strip are caused to lay into even close contact with the wickmembers 49. After a predetermined interval the strips are in conditionfor application of a sample for electrophoretic or ionophoreticseparation. This operation involves the removal of the closure 56followed by application of a predetermined amount ofthe sample to eachof the strips, the sample being carefully and evenly applied to a narrowregion immediately overlying the uppermost one of the rods 29. Anelectrical current of a predetermined value is now applied to theterminals 19, whereby current ow occurs through the electrolyte of eachof the paper strips. This results in separation of certain constituentsof the sample in a manner well known to those familiar withelectrophoresis equipment. After a period lof time sufiicient forcompletion of the separation desired, the current is discontinued, thecover 53 removed, and the sides of the rack 32 swung upwardly followedby removal of the rack 32. Initial outward movement of the two sides yofthe rack 32 causes a shearing away of the extremities of fthe stripsfrom the wick members 49. When the two sides of the rack 4are swung outto a common planepas shown in solid lines in Figure 3, the strips aretaut, the pattern area hanging free from contact with any support. Theextended rack can now be introduced into a suitable drying oven, to holdthe strips while they are being dried.

y The drying can be followed by application of dyeing solutions, ollowedby nal drying, all while the strips are supported upon the rack 32.

Referring to Figures 5 and 6, we have shown an embodiment of ourapparatus which does not employ a groove 1S and communicating ducts 16for equalization of the liquid level. Instead, the ducts 61 and 62located atopposite ends of the cell and, above the level of the liquidprovide means for equalization of the liquid level. Prior to commencinga run, one end of the cell is lifted to allow the liquid to cover one ofthe ducts 61 and 62. When the liquid level is equalized, the -cell isthen lowered and the run is commenced. Thus, any possibility ofdiffusion between the cells is eliminated. Further, there is no currentpath between the cells other than the one which includes current flowthrough the electrolyte of the electrophoresis strips.

It will be evident from the foregoing that we have provided apparatushaving many advantages over the conventional equipment previouslydescribed. The two cells are selt-equalizing with respect to theelectrolyte levels. There is no excessive wetting of the lower ends ofthe paper strips because they do not dip directly into the electrolyte.There is a shearing away action as the strips are removed from contactwith the wick members 49, and as a result the strips do not haveexcessive amounts of electrolyte at their extremities. The hinged rack32 greatly facilitates both application and removal of the paper strips,and also the handling of these strips during drying. Further, becausethe strips `are horizontal and taut they dry with practically no shiftof the resolved zone.

We claim:

1. ln paper strip electrophoresis apparatus, container means formingytwo cells for electrolyte, a rack comprising two side portions hingedlyconnected together, said side portions -having means thereon forengaging end portions of paper strips, support means carried by thecontainer means for supporting said rack and said strips with the sideportions vof the rack swung downwardly to thereby establish electricalcontact between the extremities of the strips and the electrolyte of thecells, said hinged rack being readily removable from said supportingmeans fat the end of a run.

2. Apparatus as in claim l in which the means for attaching the endportions of the paper strips to the hinged rack include studs looselyengaged in apertures formed in the strips.

3. In paper strips electrophoresis apparatus, container means formingtwo cells for electrolyte, rack supporting means carried by thecontainer means, a hinged rack removably carried by said supportingmeans, said hinged rack comprising two side portions hingedly connectedtogether and having means thereon for engaging the end portions of paperstrips, saidrsupporting means including elements adapted to engage thebent middle portions of the strips for supporting the same when thehinged rack with the strips is applied to the apparatus, and means forestablishing electrical connection between the extremities of the stripand the electrolyte ofthe cells.

4. Apparatus as in claim 3 in which said last-named means comprises wickmembers formed of absorbent sheet material having their lower edgesadapted to be immersed in the electrolyte and their upper edges adaptedto form overlapping contact with the lower extremities of the paperstrips.

5. In paper strip electrophoresis apparatus, container means partitionedby a dividing wall to formtwo cells for electrolyte, rack-supportingmeans carried by the container, a hinged rack removably carried by saidsupporting means, said hinged rack comprising two side portions hingedlyconnected together and having means thereon for engaging the endportions of paper strips, said supporting means including elementsadapted to engage the bent middle portions of the strips for supportingthe same when the hinged rack with the strips is applied to theapparatus, and means for establishing electrical connection between theextremities of the strips and the electrolyte of the cells.

6. Apparatus as in claim 5 in which said last-named means comprises wickmembers formed of absorbent sheet material having their lower edgesadapted to be immersed in the electrolyte and their upper edges adaptedto form overlapping contact with the lower extremities of the paperstrips, and wherein said means for equalizing or" the liquid level insaid cell comprises ducts formed in said wall, said ducts beingpositioned in said dividing wall at the ends of said cells and abovethat portion of said wall adapted to be covered by the electrolyte.

7. In paper strip electrophoresis apparatus, container means forming twocells for electrolyte, means for supporting the paper strip in a regiongenerally overlying the cells with the extremities of the stripdepending toward the cells, at least one wall mounted in each cell, andwicl; members of absorbent material removably carried by said walls, thelower edges of said wick members adapted to be immersed in theelectrolyte carried by the cells and the upper edges terminating shortof the uppermost extension of the paper strip and adapted to form anoverlapping contact with the lower extremities of the paper strip.

8. In paper strip electrophoresis apparatus, container means forming twocells for electrolyte, means for supporting the paper strip in a regiongenerally overlying the cells with the extremities of the stripdepending toward the cells, and a wick member of absorbent materialsupported in each of said cells and adapted to form an intermediateportion between the ends of the strip and the electrolyte, the loweredges of said wick members adapted to be immersed in the electrolytecarried by the cells and the upper edges being spaced apart and adaptedto form an overlapping contact with the lower extremities of the paperstrip.

References Cited in the le of this patent FOREIGN PATENTS 647,630 GreatBritain Dec. 20, 1950 1,057,440 France Oct. 28, 1953 842,863 GermanyJuly 3, 1952 865,379 Germany Feb. 2, 1953 OTHER REFERENCES Durrum:Journal American Chem. Soc., vol. 72 (1950), pages 2943 to 2948.

1. IN PAPER STRIP ELECTROPHORESIS APPARATUS, CONTAINER MEANS FORMING TWOCELLS FOR ELECTROLYTE, A RACK COMPRISING TWO SIDE PORTIONS HINGEDLYCONNECTED TOGETHER, SAID SIDE PORTIONS HAVING MEANS THEREON FOR ENGAGINGEND PORTION OF PAPER STRIPS, SUPPORT MEANS CARRIED BY THE CONTAINERMEANS FOR SUPPORTING SAID RACK AND SAID STRIPS WITH THE SIDE PORTIONS OFTHE RACK SWUNG DOWNWARDLY TO THEREBY ESTABLISH ELECTRICAL CONTACTBETWEEN THE EXTREMITIES OF THE STRIPS AND THE ELECTROLYTE OF THE CELLS,SAID HINGED RACK BEING READILY REMOVABLE FROM SAID SUPPORTING MEANS ATTHE END OF A RUN.